151 research outputs found
Superstring Relics, Supersymmetric Fragmentation and UHECR
Superstring theory predicts the existence of relic metastable particles whose
average lifetime is longer than the age of the universe and which could, in
principle, be good dark matter candidates. At the same time, these states would
be responsible for the Ultra High Energy Cosmic Rays (UHECR) events which will
be searched for by various experimental collaborations in the near future. We
describe a possible phenomenological path which could be followed in order to
search for new physics in their detection.Comment: 7 pages 4 Figs. Plenary Talk presented by Claudio Coriano' at the 1st
Intl. Conf. on String Phenomenology, Oxford, UK, July 6-11, 200
EARTH'S MAGNETISM AT THE SOUTH POLE: A VIEW FROM INLAND AND COASTAL STATIONS AND FROM TEMPORARY INSTALLATIONS
Contributions to the knowledge of the Earth’s magnetism from polar regions is extremely important to understand the planetary phenomena which occur both below and above the Earth’s surface. At those areas the Earth’s magnetic field is stronger and the spatial and temporal changes are enhanced. At the same time polar regions are areas scarcely covered by observations for the adverse environmental conditions. We report the experience gained in years of management and maintenance of permanent stations (Mario Zucchelli, Dumont d’Urville (Victoria Land) and Concordia stations, Dome C) as well as temporary installations (Talos Dome) in Antarctica, showing how different acquisition systems, analysis and interpretation of data allow the scientific communities to contribute to originating important theories, models and results
Ground magnetometric surveys end integrated geophysical methods for solid buried waste detection: a case study
The detection of illegal buried waste by means of geophysical techniques has recently become a major effort in shallow geophysical investigations. In particular, detection and location of underground metallic storage tanks can be accomplished using different instruments and techniques. In this paper we describe the results of an investigation carried out in a tuff quarry in Riano Flaminio (north Rome, Italy). A preliminary magnetometric survey revealed the existence of anomalous zones in the analysed region. Excavation in some of the selected areas confirmed that the anomalies were generated by underground magnetic material: over 160 steel drums were found. After their removal, a new magnetometric survey was performed. On the basis of the new map, a multifrequency induction survey, a geoelectrical profile and GPR measurements were taken to extend the characterization of the subsoil
The Kinetic Interpretation of the DGLAP Equation, its Kramers-Moyal Expansion and Positivity of Helicity Distributions
According to a rederivation - due to Collins and Qiu - the DGLAP equation can
be reinterpreted (in leading order) in a probabilistic way. This form of the
equation has been used indirectly to prove the bound
between polarized and unpolarized distributions, or positivity of the helicity
distributions, for any . We reanalize this issue by performing a detailed
numerical study of the positivity bounds of the helicity distributions. To
obtain the numerical solution we implement an x-space based algorithm for
polarized and unpolarized distributions to next-to-leading order in ,
which we illustrate. We also elaborate on some of the formal properties of the
Collins-Qiu form and comment on the underlying regularization, introduce a
Kramers-Moyal expansion of the equation and briefly analize its Fokker-Planck
approximation. These follow quite naturally once the master version is given.
We illustrate this expansion both for the valence quark distribution and
for the transverse spin distribution .Comment: 38 pages, 27 figures, Dedicated to Prof. Pierre Ramond for his 60th
birthda
Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC
During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base
Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates:
80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field
were carried out only during summer expeditions. Since 1991 the recording was implemented with an
automatic acquisition system operating through the year. More recently,after two short test surveys, from
October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C,
DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic
coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained
from TNB observations coming from almost twenty years of observations and also the preliminary results
obtained from the analysis of the first year of data from DMC
Fast geophysical prospecting applied to archaeology: results at «Villa ai Cavallacci» (Albano Laziale, Rome) site
The present essay is the result of a cooperative work between geophysicists and archaeologists in which the authors
carried out an integrated geophysical prospecting in an archaeological site near Rome. This paper describes the
methodology and the results of a geophysical survey carried out on Villa ai Cavallacci, an ancient roman building in
Albano Laziale (Rome) discovered in the late seventies. It is often possible to obtain very important results planning
a fast geophysical survey opportunely; within this framework (due to the fact that an archaeological excavation was
planned in a short time), an integrated geophysical techniques survey (GPR, magnetic, and geoelectric tomography)
has been carried out on the areas indicated by the archaeologists. Even if the described geophysical survey should be
considered only a first step analysis, the data pointed out some very interesting features confirmed by the excavation
Fourteen years of geomagnetic daily variation at Mario Zucchelli Station (Antarctica)
During the 1986-87 austral summer a geomagnetic observatory was installed
at the Italian Antarctic Base Mario Zucchelli Station. In the first three years
continuous time variation monitoring and absolute measurements of the
geomagnetic field were carried out only during summer expeditions. Starting
1991 an automatic acquisition system, operating through all the year, was put
in operation. We present here some peculiarities of the daily variation as
observed for fourteen years (1987-2000). The availability of a long series of
data has allowed the definition of seasonal, as well as solar cycle effects, on
short time variations as observed at a cusp-cap observatory. In particular,
contrary to mid latitude behaviour, a clear dependence of the daily variation
amplitude on the global geomagnetic K index was well defined
Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC
During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base
Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates:
80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field
were carried out only during summer expeditions. Since 1991 the recording was implemented with an
automatic acquisition system operating through the year. More recently,after two short test surveys, from
October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C,
DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic
coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained
from TNB observations coming from almost twenty years of observations and also the preliminary results
obtained from the analysis of the first year of data from DMC
Fourteen years of geomagnetic daily variation at Mario Zucchelli Station (Antarctica)
During the 1986-87 austral summer a geomagnetic observatory was installed
at the Italian Antarctic Base Mario Zucchelli Station. In the first three years
continuous time variation monitoring and absolute measurements of the
geomagnetic field were carried out only during summer expeditions. Starting
1991 an automatic acquisition system, operating through all the year, was put
in operation. We present here some peculiarities of the daily variation as
observed for fourteen years (1987-2000). The availability of a long series of
data has allowed the definition of seasonal, as well as solar cycle effects, on
short time variations as observed at a cusp-cap observatory. In particular,
contrary to mid latitude behaviour, a clear dependence of the daily variation
amplitude on the global geomagnetic K index was well defined
Geomagnetic polar observatories: the role of Concordia station at Dome C, Antarctica
A geomagnetic observatory is a permanent facility where magnetic
declination and inclination are recorded in conjunction with the temporal
evolution of the magnetic field components. Polar regions are
scarcely covered by observational points then the contributions from observatories
located there are particularly relevant. The geomagnetic observatory
at Concordia station, Dome C - Antarctica is located in the
inner part of the continent, its position is favorable for two key reasons,
i) data are unaltered by the "coastal effect” and ii) crustal effect
is negligible due to the thickness, almost 3 km, of ice coverage. Nevertheless,
these latter conditions imply an unconsidered aspect which
characterizes the entire station and every structure laying on the ice
surface: the dome on which Concordia station resides is sliding horizontally
and moving vertically with a velocity of few millimeter to
centimeters per year as indicated by independent geodetic observations.
This slow and continuous movement has a puzzling effect on the
trend of horizontal components of the magnetic field, sampled in a
time window of a decade since the establishing of the observatory in
2005.During the International Polar Year (2007-2009) the observatory
was upgraded with new equipment fulfilling the requirements of the
Intermagnet consortium, and becoming an observatory member in
2011. In this paper are illustrated the strategy adopted to track any possible
displacement of the observatory reference points (i.e. the azimuth
mark, the pillar position) and all the ordinary and extraordinary actions
required for collecting high quality data
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